JPS59217254A - Phase modifying device of vtr - Google Patents

Abstract

PURPOSE:To vary relatively phase relation between a tape timer value and a servo reference and to prevent an error in phase modification by grasping the phase relation between the both in the 1st phase modifying operation, and adjusting a tape speed in the 2nd phase adjusting operation according to the phase relation grasped in the 1st operation when the phase modification is necessary in the 2nd or succeeding operation. CONSTITUTION:A phase detecting circuit 5 detects the phase relation between a tape timer value and the servo reference during the phase modification of tape timer editing, and a tape speed adjusting cirlcuit 4 adjusts the tape speed according to the output signal of the phase detecting circuit 5. If a timer value comparing circuit 3 operates after the tape speed adjusting circuit 4 operates, the phase detecting circuit 5 performs the 2nd tape speed control. In this case, a signal of, for example, every quarter frame is received from tape timer circuit 1 and the tape speed adjusting circuit 4 is indicated so as to shift the timing of a control signal in the positive or negative directions by a quarter frame. Thus, the probability of coincidence increases in the 2nd operation.

Description

[Detailed description of the invention] The present invention relates to a phase adjusting device for a VTR.

Conventional VTR WAIl equipment includes a tape timer
A device employing the laIIA method is known. This tape timer editing method applies the following principle to issue a collection of commands. That is, a tape roller uses two-phase tack pulses with a phase difference of 90 traces,
The timer value is repited to rOJ at the editing point on the tape, and the rewinding time during which the tape is rewound for a certain period of time is called pre-0-reel time. ), run the tape in editing mode. This allows the counter to detect the relative position from the retted edit point.

This method is advantageous in that the tape editing point can be easily corrected by shifting the contents of the counter by 1, and there is no need to write an address such as a time-1 address on the tape. However, after deciding the editing point,
It has a disadvantage that if the tape running is repeatedly reversed, etc., the Ii convergence point on the tape shifts. This drawback is that tape 0
This is caused by idling of the tape roller due to separation between the roller and the tape, or by low accuracy in detecting up and down signals on the counter.

However, in the current VTR m soso 4 J3, tape 0
- The above drawbacks have been largely eliminated by improving the contact between the tape and the tape and improving the resolution of the timer.

To explain the contents of the actual editing work, first, there are a playback VTR and a recording VTR that serve as editing materials.

Then, both start editing at Enoki who called pre-roll for the same time at the edit point, and perform editing recording at the edit point.By the way, depending on the accuracy and rise speed of the pre-roll point of both VTRs, the actual In some cases, a shift occurred in the IQ concentration point of the IQ point.As a method to prevent this shift, an operation called phasing is performed.
This refers to matching the phases of both VTRs.

As a general phase adjustment device, the recording side VTR is used as a reference,
In contrast, the phase of the reproducing VTR is adjusted. That is, the tape speed is controlled by a speed adjustment signal sent to the VTR, and when the tape timer values of both tapes match, the control is stopped, thereby matching the phases of both.

FIG. 1(a) is a block diagram of a conventional phase adjusting device. The tape timer circuit 1 receives timer pulses φ1. Simultaneous reproduction output of φ2 (for example, a pulse having a frequency of 1920 Hz during reproduction) and control track signal @ (CT signal) (CONF CTL signal: 301-I during reproduction)
A signal having a frequency of Z) is input. The tape running direction is determined by timer pulses φ1 and φ2.
By dividing the frequency by 4, the frame pulse signal s (3°1
-1z) and corrects it using the C0NF C1-1 signal.

At the edit point, the tape timer value is reset rOJ, and the relative position from the edit point can be known during editing. The tape timer value in units of frames output from the tape timer circuit 1 is input to one input terminal of the timer value comparison circuit 3, and the timer value of the reference timer value comparison circuit 2 is input to the other input terminal. .

The reference timer value from this reference timer circuit 2 is
It may be the timer value of TR (for example, on the recording side), or it may be a value obtained by adding a minus to the time to point aS, rather than using an internal timer. In short, the only problem is the time required for both VTRs to reach the editing point, and if the internal timers operate at the same time, the problem is the same.

After completing the preroll, while driving to the edit point (actually,
(up to 3 seconds before the editing point), compare the two, and if they match, no signal is sent to the tape speed adjustment circuit 4, and if they do not match, the tape speed is adjusted until the two match. The circuit is sent.

V"111 is applied to the tape speed adjustment circuit 4, and specifically, it is approximately +13% or approximately -13% relative to the playback speed.
% tape running is performed, and when the vk semi-timer value and the tape timer value match, the process returns to playback running. that time,
Since the servo locks to a nearby reference, there is no guarantee that the reference timer value and tape timer value will match at this locking point; if they do not match, the comparison circuit 3 will operate again and repeat the same operation C1. That will happen. This operation is performed during the effective phase adjustment operation (from completion of pre-roll to HA).
(Until 3 seconds before the convergence point) You can repeat it as many times as you like. This is because the phase relationship between the tape timer value and the m quasi-timer value does not change at that time.

As described above, the cause of the phase adjustment error in the conventional tape timer m1 method is not only due to the idle rotation of the tape or the resolution of the counter, but also because the phase relationship between the tape timer value and the servo reference is not constant. In other words, if the phase relationship between the change point of the tape timer value and the reference of the servo is not constant, if the tape speed adjustment control is stopped when the tape timer value matches, the This means that there is no guarantee as to which direction to lock it to. This results in a phase shift.

In this case, unless there is a change in the phase relationship between the tape timer value change point and the servo reference, once a phase adjustment error occurs, the same harmonization error will be repeated in subsequent phase adjustment operations. There is a problem.

The present invention has been made by focusing on the above-mentioned conventional problems, and in the phase adjustment 'IAi' of VTR tape timer editing,
It is an object of the present invention to provide a phase adjustment device for a VTR that can prevent phase adjustment errors that occur in the past due to an inconsistent phase relationship between the tape timer value and the vore reference.

In order to achieve this purpose, the present invention grasps the phase relationship during the first phase adjustment operation, and if phase adjustment is required from the second time onwards, the second phase adjustment operation is performed according to the phase relationship determined at the first time. By adjusting the tape speed during phase adjustment work, the phase relationship between the two is relatively changed to prevent harmonization errors.

Hereinafter, the wood construction will be described in detail based on the embodiments shown in the accompanying drawings. FIG. 1(b) is a block diagram showing one embodiment of the present invention. The same members as those in the conventional example shown in FIG. 1(a) are designated by the same reference numerals, and the explanation thereof will be omitted.

Basically, it is the same as Fig. 1(a), but the difference is that a phase detection circuit 5 is newly installed to detect the phase relationship between the tape timer value and the servo reference when adjusting the phase during tape timer editing. , the tape speed adjustment circuit 4 is different in that the tape speed is adjusted in accordance with the output signal of the phase detection circuit 5.

Next, the operation of the above embodiment will be explained.

Operations other than the phase detection circuit 5 are similar to those shown in FIG. 1(a).

If the timer value comparison circuit 3 operates after the tape speed adjustment circuit 4 is turned on, when the second tape speed control is performed by the phase detection circuit 5, the tape timer circuit 1, for example, receive signals in units of units,
Instructs the tape speed adjustment circuit 4 to change the control signal timing in one direction (1/4 frame) or in one direction. The above judgment is determined depending on which direction the tape timer value deviates from the reference timer value as a result of the first harmonization. If you write this J: sea urchin, the probability of matching will be higher the second time.

If there is a mismatch, the probability of a match will be further improved by shifting the timing by 1/4 frame in the same direction or in one direction for the third time. Even in the worst case, if the fourth frame timing shift is J:, the mismatch will disappear. In this way, the timer value comparison circuit 3 finally matches the tape timer value and the JJIle timer value,
When this becomes stable, the phase adjustment work is completed.

As described above, the present invention can prevent phase adjustment errors that occur conventionally due to the inconsistent phase relationship between the tape timer value and the servo reference in a phase adjustment device for VTR tape timer editing. It has this effect.

[Brief explanation of drawings]

FIG. 1(a) is a block diagram showing a conventional VTR harmonizer, and FIG. 2 is a block diagram showing an embodiment of the present invention. 1...Tape timer circuit, 2...Reference timer circuit,
3...Timer value comparison circuit, 4...Tape speed adjustment circuit, 5...Phase detection circuit. Patent Applicant: NEC Co., Ltd. Procedural Amendment (Method) 1981 1) +4, Mr. Commissioner of the Japan Patent Office 1, Indication of Case Patent Application No. 1989-90175 1 No. 2, U″′1°” VTR+7)li [i! J13
, person who makes corrections

Claims (1)

[Claims] a phase detection circuit that detects the phase relationship between the tape timer value and the servo reference when the tape timer aS is harmonized;
A VIR harmonizing device comprising a tape speed adjustment circuit that adjusts the tape speed according to the output signal of the phase detection circuit.